Extrusion process for manufacturing a Z-directed component for a printed circuit board

ABSTRACT

A method for manufacturing a Z-directed component for insertion into a mounting hole in a printed circuit board according to one example embodiment includes extruding a substrate material according to the shape of the Z-directed component. A conductive material is then selectively applied to the extruded substrate material and the Z-directed component is formed from the extruded substrate material.

CROSS REFERENCES TO RELATED APPLICATIONS

This patent application is related to U.S. patent application Ser. No.13/222,748, filed Aug. 31, 2011, entitled “Die Press Process forManufacturing a Z-Directed Component for a Printed Circuit Board,” U.S.patent application Ser. No. 13/222,418, filed Aug. 31, 2011, entitled“Screening Process for Manufacturing a Z-Directed Component for aPrinted Circuit Board,” U.S. patent application Ser. No. 13/222,376,filed Aug. 31, 2011, entitled “Spin Coat Process for Manufacturing aZ-Directed Component for a Printed Circuit Board,” and U.S. patentapplication Ser. No. 13/284,084, filed Oct. 28, 2011, entitled“Continuous Extrusion Process for Manufacturing a Z-Directed Componentfor a Printed Circuit Board,” which are assigned to the assignee of thepresent application.

BACKGROUND

1. Field of the Disclosure

The present invention relates generally to processes for manufacturingprinted circuit board components and more particularly to an extrusionprocess for manufacturing a Z-directed component for a printed circuitboard.

2. Description of the Related Art

The following co-pending United States patent applications, which areassigned to the assignee of the present application, describe various“Z-directed” components that are intended to be embedded or insertedinto a printed circuit board (“PCB”): Ser. No. 12/508,131 entitled“Z-Directed Components for Printed Circuit Boards,” Ser. No. 12/508,145entitled “Z-Directed Pass-Through Components for Printed CircuitBoards,” Ser. No. 12/508,158 entitled “Z-Directed Capacitor Componentsfor Printed Circuit Boards,” Ser. No. 12/508,188 entitled “Z-DirectedDelay Line Components for Printed Circuit Boards,” Ser. No. 12/508,199entitled “Z-Directed Filter Components for Printed Circuit Boards,” Ser.No. 12/508,204 entitled “Z-Directed Ferrite Bead Components for PrintedCircuit Boards,” Ser. No. 12/508,215 entitled “Z-Directed SwitchComponents for Printed Circuit Boards,” Ser. No. 12/508,236 entitled“Z-Directed Connector Components for Printed Circuit Boards,” and Ser.No. 12/508,248 entitled “Z-Directed Variable Value Components forPrinted Circuit Boards.”

As densities of components for printed circuit boards have increased andhigher frequencies of operation are used, some circuits' designs havebecome very difficult to achieve. The Z-directed components described inthe foregoing patent applications are designed to improve the componentdensities and frequencies of operation. The Z-directed components occupyless space on the surface of a PCB and for high frequency circuits, e.g.clock rates greater than 1 GHz, allow for higher frequency of operation.The foregoing patent applications describe various types of Z-directedcomponents including, but not limited to, capacitors, delay lines,transistors, switches, and connectors. A process that permits massproduction of these components on a commercial scale is desired.

SUMMARY

A method for manufacturing a Z-directed component for insertion into amounting hole in a printed circuit board according to a first exampleembodiment includes extruding a substrate material according to theshape of the Z-directed component. A conductive material is thenselectively applied to the extruded substrate material and theZ-directed component is formed from the extruded substrate material.

A method for manufacturing a Z-directed component for insertion into amounting hole in a printed circuit board according to a second exampleembodiment includes extruding a substrate material through an extrusiondie having a chamber defining the shape of the extruded substratematerial. This includes forming at least one channel through thesubstrate material with a corresponding projection in the extrusion die.The extruded substrate material is divided into a plurality of layers ofthe Z-directed component according to the thickness of each layer. Aconductive material is applied to a surface of at least one of thelayers and a stack of the layers is combined to form the Z-directedcomponent.

BRIEF DESCRIPTION OF THE DRAWINGS

The above-mentioned and other features and advantages of the variousembodiments, and the manner of attaining them, will become more apparentand will be better understood by reference to the accompanying drawings.

FIG. 1 is a perspective view of a Z-directed component according to oneexample embodiment.

FIG. 2 is a transparent perspective view of the Z-directed componentshown in FIG. 1 illustrating the internal arrangement of elements of theZ-directed component.

FIGS. 3A-3F are perspective views showing various example shapes for thebody of a Z-directed component.

FIGS. 4A-4C are perspective views showing various example side channelconfigurations for a Z-directed component.

FIGS. 5A-5H are perspective views showing various example channelconfigurations for the body of a Z-directed component.

FIG. 6A is a perspective view of a Z-directed component having O-ringsfor connecting to internal layers of a PCB and having a body havingregions comprised of similar and/or dissimilar materials according toone example embodiment.

FIG. 6B is a top plan view of the Z-directed component shown in FIG. 6A.

FIG. 6C is a schematic side elevation view of the Z-directed componentshown in FIG. 6A.

FIG. 7 is a schematic illustration of various example elements orelectronic components that may be provided within the body of aZ-directed component in series with a conductive channel.

FIG. 8 is a schematic cross-sectional view of a Z-directed componentflush mounted in a PCB showing conductive traces and connections to theZ-directed component according to one example embodiment.

FIG. 9 is a top plan view of the Z-directed component and PCB shown inFIG. 8.

FIG. 10 is a schematic cross-sectional view of a Z-directed componentflush mounted in a PCB showing ground loops for the Z-directed componentwith the Z-directed component further having a decoupling capacitorwithin its body according to one example embodiment.

FIG. 11 is a schematic cross-sectional view of a Z-directed componentflush mounted in a PCB showing a Z-directed component for transferring asignal trace from one internal layer of a PCB to another internal layerof that PCB according to one example embodiment.

FIG. 12 is a perspective view of a Z-directed capacitor havingsemi-cylindrical sheets according to one example embodiment.

FIG. 13 is an exploded view of another embodiment of a Z-directedcapacitor having stacked discs according to one example embodiment.

FIGS. 14A and 14B are perspective views of an extrusion die for formingthe layers of a Z-directed component according to one exampleembodiment.

FIG. 15A is a perspective cutaway view showing the recombination of apair of extruded segments formed by the extrusion die shown in FIGS. 14Aand 14B.

FIG. 15B is a perspective cutaway view showing the use of a movableelement to aid in recombining of a pair of extruded segments formed bythe extrusion die shown in FIGS. 14A and 14B.

FIG. 16 is a perspective view of an extrusion die for forming the layersof a Z-directed component according to another example embodiment.

FIG. 17 is perspective view of a series of blades for dividing extrudedsubstrate material into individual layers according to one exampleembodiment.

FIG. 18 is a perspective view of a layer of the Z-directed componentformed from the extrusion die shown in FIGS. 14A and 14B.

FIG. 19 is a perspective view of a layer of a Z-directed component in aconstraining plate with a gap formed between a side wall surface of theconstraining plate and a side channel of the layer according to oneexample embodiment.

FIG. 20 is a schematic view of a mask for applying conductive materialto a layer of a Z-directed component according to one exampleembodiment.

FIG. 21 is a perspective view of a layer of a Z-directed componenthaving conductive material applied through the mask shown in FIG. 20 toa top surface of the layer.

FIGS. 22A and 22B are perspective views of opposite ends of a Z-directeddecoupling capacitor formed according to an extrusion manufacturingprocess according to one example embodiment.

FIG. 23 is a perspective view of a Z-directed component having offsetside channels according to one example embodiment.

FIG. 24 is a perspective cutaway view of a stack of layers of aZ-directed component being compressed in a constraining according to oneexample embodiment.

FIG. 25A is a perspective view of a Z-directed component having a domeformed on an end thereof according to one example embodiment.

FIG. 25B is a perspective view of a Z-directed component having achamfered end according to one example embodiment.

FIG. 26 is a perspective view of a plug for forming a taper in an end ofa Z-directed component according to one example embodiment.

FIG. 27 is a perspective view of a bottom surface of a PCB having anadhesive applied thereto in contact with a side surface of a Z-directedcomponent inserted into a mounting hole in the PCB according to oneexample embodiment.

FIG. 28A is a perspective view of a Z-directed component inserted into amounting hole in a PCB, the Z-directed component having a conductivestrip applied to a side surface thereof according to one exampleembodiment.

FIG. 28B is a side cutaway view of the Z-directed component and PCBshown in FIG. 28A.

DETAILED DESCRIPTION

The following description and drawings illustrate embodimentssufficiently to enable those skilled in the art to practice the presentinvention. It is to be understood that the disclosure is not limited tothe details of construction and the arrangement of components set forthin the following description or illustrated in the drawings. Theinvention is capable of other embodiments and of being practiced or ofbeing carried out in various ways. For example, other embodiments mayincorporate structural, chronological, electrical, process, and otherchanges. Examples merely typify possible variations. Individualcomponents and functions are optional unless explicitly required, andthe sequence of operations may vary. Portions and features of someembodiments may be included in or substituted for those of others. Thescope of the application encompasses the appended claims and allavailable equivalents. The following description is, therefore, not tobe taken in a limited sense and the scope of the present invention isdefined by the appended claims.

Also, it is to be understood that the phraseology and terminology usedherein is for the purpose of description and should not be regarded aslimiting. The use of “including,” “comprising,” or “having” andvariations thereof herein is meant to encompass the items listedthereafter and equivalents thereof as well as additional items. Unlesslimited otherwise, the terms “connected,” “coupled,” and “mounted,” andvariations thereof herein are used broadly and encompass direct andindirect connections, couplings, and mountings. In addition, the terms“connected” and “coupled” and variations thereof are not restricted tophysical or mechanical connections or couplings.

Overview of Z-Directed Components

An X-Y-Z frame of reference is used herein. The X and Y axes describethe plane defined by the face of a printed circuit board. The Z-axisdescribes a direction perpendicular to the plane of the circuit board.The top surface of the PCB has a zero Z-value. A component with anegative Z-direction value indicates that the component is inserted intothe top surface of the PCB. Such a component may be above (extend past),flush with, or recessed below either the top surface and/or the bottomsurface of the PCB. A component having both a positive and negativeZ-direction value indicates that the component is partially insertedinto the surface of the PCB. The Z-directed components are intended tobe inserted into a hole or recess in a printed circuit board. Dependingon the shape and length of the component(s), more than one Z-directedcomponent may be inserted into a single mounting hole in the PCB, suchas being stacked together or positioned side by side. The hole may be athrough hole (a hole from the top surface through to the bottomsurface), a blind hole (an opening or recess through either the top orbottom surface into an interior portion or internal layer of the PCB) oran internal cavity such that the Z-directed component is embedded withinthe PCB.

For a PCB having conductive traces on both external layers, one externallayer is termed the top surface and the other the bottom surface. Whereonly one external layer has conductive traces, that external surface isreferred to as the top surface. The Z-directed component is referred toas having a top surface, a bottom surface and a side surface. Thereferences to top and bottom surfaces of the Z-directed componentconform to the convention used to refer to the top and bottom surfacesof the PCB. The side surface of a Z-directed component extends betweenthe top and bottom surfaces of the PCB and would be adjacent to the wallof the mounting hole in the PCB where the mounting hole is perpendicularto the face of the PCB. This use of top, bottom and side should not betaken as limiting how a Z-directed component may be mounted into a PCB.Although the components are described herein as being mounted in aZ-direction, this does not mean that such components are limited tobeing inserted into a PCB only along the Z-axis. Z-directed componentsmay be mounted normal to the plane of the PCB from the top or bottomsurfaces or both surfaces, mounted at an angle thereto or, depending onthe thickness of the PCB and the dimensions of the Z-directed component,inserted into the edge of the PCB between the top and bottom surfaces ofthe PCB. Further, the Z-directed components may be inserted into theedge of the PCB even if the Z-directed component is wider than the PCBis tall as long as the Z-directed component is held in place.

The Z-directed components may be made from various combinations ofmaterials commonly used in electronic components. The signal connectionpaths are made from conductors, which are materials that have highconductivity. Unless otherwise stated, reference to conductivity hereinrefers to electrical conductivity. Conducting materials include, but arenot limited to, copper, gold, aluminum, silver, tin, lead and manyothers. The Z-directed components may have areas that need to beinsulated from other areas by using insulator materials that have lowconductivity like plastic, glass, FR4 (epoxy & fiberglass), air, mica,ceramic and others. Capacitors are typically made of two conductingplates separated by an insulator material that has a high permittivity(dielectric constant). Permittivity is a parameter that shows theability to store electric fields in the materials like ceramic, mica,tantalum and others. A Z-directed component that is constructed as aresistor requires materials that have properties that are between aconductor and insulator having a finite amount of resistivity, which isthe reciprocal of conductivity. Materials like carbon, dopedsemiconductor, nichrome, tin-oxide and others are used for theirresistive properties. Inductors are typically made of coils of wires orconductors wrapped around a material with high permeability.Permeability is a parameter that shows the ability to store magneticfields in the material which may include iron and alloys likenickel-zinc, manganese-zinc, nickel-iron and others. Transistors such asfield effect transistors (“FET5”) are electronic devices that are madefrom semiconductors that behave in a nonlinear fashion and are made fromsilicon, germanium, gallium arsenide and others.

Throughout the application there are references that discuss differentmaterials, properties of materials or terminology interchangeably ascurrently used in the art of material science and electrical componentdesign. Because of the flexibility in how a Z-directed component may beemployed and the number of materials that may be used, it is alsocontemplated that Z-directed components may be constructed of materialsthat have not been discovered or created to date. The body of aZ-directed component will in general be comprised of an insulatormaterial unless otherwise called out in the description for a particulardesign of a Z-directed component. This material may possess a desiredpermittivity, e.g., the body of a capacitor will typically be comprisedof an insulator material having a relatively high dielectric constant.

PCBs using a Z-directed component may be constructed to have a singleconductive layer or multiple conductive layers as is known. The PCB mayhave conductive traces on the top surface only, on the bottom surfaceonly, or on both the top and bottom surfaces. In addition, one or moreintermediate internal conductive trace layers may also be present in thePCB.

Connections between a Z-directed component and the traces in or on a PCBmay be accomplished by soldering techniques, screening techniques,extruding techniques or plating techniques known in the art. Dependingon the application, solder pastes and conductive adhesives may be used.In some configurations, compressive conductive members may be used tointerconnect a Z-directed component to conductive traces found on thePCB.

The most general form of a Z-directed component comprises a body havinga top surface, a bottom surface and a side surface, a cross-sectionalshape that is insertable into a mounting hole of a given depth D withina PCB with a portion of the body comprising an insulator material. Allof the embodiments described herein for Z-directed components are basedon this general form.

FIGS. 1 and 2 show an embodiment of a Z-directed component. In thisembodiment, Z-directed component 10 includes a generally cylindricalbody 12 having a top surface 12 t, a bottom surface 12 b, a side surface12 s, and a length L generally corresponding to the depth D of themounting hole. The length L can be less than, equal to or greater thanthe depth D. In the former two cases, Z-directed component 10 would inone case be below at least one of the top and bottom surfaces of the PCBand in the other it may be flush with the two surfaces of the PCB. Wherelength L is greater than depth D, Z-directed component 10 would not beflush mounted with at least one of the top and bottom surfaces of thePCB. However, with this non-flush mount, Z-directed component 10 wouldbe capable of being used to interconnect to another component or anotherPCB that is positioned nearby. The mounting hole is typically athrough-hole extending between the top and bottom surfaces of the PCBbut it may also be a blind hole. When recessed below the surface of thePCB, additional resist areas may be required in the hole of the PCB tokeep from plating the entire circumferential area around the hole.

Z-directed component 10 in one form may have at least one conductivechannel 14 extending through the length of body 12. At the top andbottom ends 14 t and 14 b of conductive channel 14, top and bottomconductive traces 16 t, 16 b are provided on the top and bottom endsurfaces 12 t, 12 b of body 12 and extend from respective ends of theconductive channel 14 to the edge of Z-directed component 10. In thisembodiment, body 12 comprises an insulator material. Depending on itsfunction, body 12 of Z-directed component 10 may be made of variety ofmaterials having different properties. These properties include beingconductive, resistive, magnetic, dielectric, or semi-conductive orvarious combinations of properties as described herein. Examples ofmaterials that have the properties are copper, carbon, iron, ceramic orsilicon, respectively. Body 12 of Z-directed component 10 may alsocomprise a number of different networks needed to operate a circuit thatwill be discussed later.

One or more longitudinally extending channels or wells may be providedon the side surface of body 12 of Z-directed component 10. The channelmay extend from one of the top surface and the bottom surface of body 12toward the opposite surface. As illustrated, two concave side wells orchannels 18 and 20 are provided in the outer surface of Z-directedcomponent 10 extending the length of body 12. When plated or soldered,these channels allow electrical connections to be made to Z-directedcomponent 10, through the PCB, as well as to internal conductive layerswithin the PCB. The length of side channels 18 or 20 may extend lessthan the entire length of body 12.

FIG. 2 shows the same component as in FIG. 1 but with all the surfacestransparent. Conductive channel 14 is shown as a cylinder extendingthrough the center of Z-directed component 10. Other shapes may also beused for conductive channel 14. Traces 16 t and 16 b can be seenextending from ends 14 t and 14 b of conductive channel 14,respectively, to the edge of body 12. While traces 16 t and 16 b areshown as being in alignment with one another (zero degrees apart), thisis not a requirement and they may be positioned as needed for aparticular design. For example, traces 16 t and 16 b may be 180 degreesapart or 90 degrees apart or any other increment.

The shape of the body of the Z-directed component may be any shape thatcan fit into a mounting hole in a PCB. FIGS. 3A-3F illustrate possiblebody shapes for a Z-directed component. FIG. 3A shows a triangularcross-sectional body 40; FIG. 3B shows a rectangular cross-sectionalbody 42; FIG. 3C shows a frusto-conical body 44; FIG. 3D shows an ovatecross-sectional cylindrical body 46; and FIG. 3E shows a cylindricalbody 48. FIG. 3F shows a stepped cylindrical body 50 where one portion52 has a larger diameter than another portion 54. With this arrangement,the Z-directed component may be mounted on the surface of the PCB whilehaving a section inserted into a mounting hole provided in the PCB. Theedges of the Z-directed component may be beveled to help with aligningthe Z-directed component for insertion into a mounting hole in a PCB.Other shapes and combinations of those illustrated may also be used fora Z-directed component as desired.

For a Z-directed component, the channels for plating can be of variouscross-sectional shapes and lengths. The only requirement is that platingor solder material make the proper connections to the Z-directedcomponent and corresponding conductive traces in or on the PCB. Sidechannels 18 or 20 may have, for example, V-, C- or U-shapedcross-sections, semi-circular or elliptical cross-sections. Where morethan one channel is provided, each channel may have the same or adifferent cross-sectional shape. FIGS. 4A-4C illustrate three sidechannel shapes. In FIG. 4A, V-shaped side channels 60 are shown. In FIG.4B, U- or C-shaped side channels 62 are shown. In FIG. 4C, wavy orirregular cross-sectional side channel shapes 65 are shown.

The numbers of layers in a PCB varies from being single sided to beingover 22 layers and may have different overall thicknesses that rangefrom less than 0.051 inch to over 0.093 inch or more. Where a flushmount is desired, the length of the Z-directed component will depend onthe thickness of the PCB into which it is intended to be inserted. TheZ-directed component's length may also vary depending on the intendedfunction and tolerance of a process. The preferred lengths will be wherethe Z-directed component is either flush with the surfaces or extendsslightly beyond the surface of the PCB. This would keep the platingsolution from plating completely around the interior of the PCB holethat may cause a short in some cases. It is possible to add a resistmaterial around the interior of a PCB hole to only allow plating in thedesired areas. However, there are some cases where it is desired tocompletely plate around the interior of a PCB hole above and below theZ-directed component. For example, if the top layer of the PCB is aV_(CC) plane and the bottom layer is a GND plane then a decouplingcapacitor would have lower impedance if the connection used a greatervolume of copper to make the connection.

There are a number of features that can be added to a Z-directedcomponent to create different mechanical and electrical characteristics.The number of channels or conductors can be varied from zero to anynumber that can maintain enough strength to take the stresses ofinsertion, plating, manufacturing processes and operation of the PCB inits intended environment. The outer surface of a Z-directed componentmay have a coating that glues it in place. Flanges or radial projectionsmay also be used to prevent over or under insertion of a Z-directedcomponent into the mounting hole, particularly where the mounting holeis a through-hole. A surface coating material may also be used topromote or impede migration of the plating or solder material. Variouslocating or orienting features may be provided such as a recess orprojection, or a visual or magnetic indicator on an end surface of theZ-directed component. Further, a connecting feature such as a conductivepad, a spring loaded style pogo-pin or even a simple spring may beincluded to add an additional electrical connection (such as frameground) point to a PCB.

A Z-directed component may take on several roles depending on the numberof ports or terminals needed to make connections to the PCB. Somepossibilities are shown in FIGS. 5A-H. FIG. 5A is a Z-directed componentconfigured as 0-port device 70A used as a plug so that if a filter or acomponent is optional then the plug stops the hole from being plated.After the PCB has been manufactured, the 0-port device 70A may beremoved and another Z-directed component may be inserted, plated andconnected to the circuit. FIGS. 5B-5H illustrate various configurationsuseful for multi-terminal devices such as resistors, diodes,transistors, and/or clock circuits. FIG. 5B shows a 1-port or singlesignal Z-directed component 70B having a conductive channel 71 through acenter portion of the component connected to top and bottom conductivetraces 72 t, 72 b. FIG. 5C shows a 1-port 1-channel Z-directed component70C where one plated side well or channel 73 is provided in addition toconductive channel 71 through the component, which is connected to topand bottom conductive traces 72 t and 72 b. FIG. 5D shows a Z-directedcomponent 70D having two side wells 73 and 75 in addition to conductivechannel 71 through the component which is connected to top and bottomtraces 72 t, 72 b. The Z-directed component 70E of FIG. 5E has threeside wells 73, 75 and 76 in addition to conductive channel 71 throughthe component, which is connected to top and bottom traces 72 t, 72 b.FIG. 5F shows Z-directed component 70F having two conductive channels 71and 77 through the component each with their respective top and bottomtraces 72 t, 72 b and 78 t, 78 b and no side channels or wells.Z-directed component 70F is a two signal device to be primarily used fordifferential signaling. FIG. 5G shows a Z-directed component 70G havingone side well 73 and two conductive channels 71 and 77 each with theirrespective top and bottom traces 72 t, 72 b and 78 t, 78 b. FIG. 5Hshows Z-directed component 70H having one conductive channel 71 with topand bottom traces 72 t, 72 b and a blind well or partial well 78extending from the top surface along a portion of the side surface thatwill allow the plating material or solder to stop at a given depth. Forone skilled in the art, the number of wells and signals is only limitedby the space, required well or channel sizes.

FIGS. 6A-C illustrate another configuration for a Z-directed componentutilizing O-rings for use in a PCB having a top and bottom conductivelayer and at least one internal conductive layer. Z-directed component150 is shown having on its top surface 150 t, a locating feature 152 anda conductive top trace 154 t extending between a conductive channel 156and the edge of body 150 d on its top surface 150 t. A conductive bottomtrace (not shown) is provided on the bottom surface. Conductive channel156 extends through a portion of the body 150 d as previously described.Located on the side surface 150 s of body 150 d is a least onesemi-circular channel or grove. As shown, a pair of axially spaced apartcircumferential channels 158 a, 158 b is provided having O-rings 160 a,160 b, respectively disposed within channels 158 a, 158 b. A portion ofthe O-rings 160 a, 160 b extend out beyond the side surface 150 s of thebody 150 d. O-rings 160 a, 160 b would be positioned adjacent one ormore of the internal layers of the PCB to make electrical contract toone or more traces provided at that point in the mounting hole for theZ-directed component. Depending on the design employed, an O-ring wouldnot have to be provided adjacent every internal layer.

O-rings 160 a, 160 b may be conductive or non-conductive depending onthe design of the circuit in which they are used. O-rings 160 a, 160 bpreferably would be compressive helping to secure Z-directed component150 within the mounting hole. The region 162 of body 150 d intermediateO-rings 160 a, 160 b may be comprised of different material than theregions 164 and 166 of the body 150 d outside of the O-rings. Forexample, if the material of region 162 is of a resistive material andO-rings 160 a, 160 b are conductive then internal circuit board tracesin contact with the O-rings 160 a, 160 b see a resistive load.

Regions 164 and 166 may also be comprised of a material having differentproperties from each other and region 162. For example, region 164 maybe resistive, region 162 capacitive and region 166 inductive. Each ofthese regions can be electrically connected to the adjoining layers ofthe PCB. Further, conductive channel 156 and traces 154 t, 154 b do notneed to be provided. So for the illustrated construction, between thetop layer of the PCB and the first internal layer from the top, aresistive element may be present in region 164, a capacitive elementbetween the first internal layer and the second internal layer in region162 and an inductive element between the second internal layer and thebottom layer of the PCB in region 166. Accordingly, for a signaltransmitted from an internal trace contacting conductive O-ring 160 a toa second internal trace contacting conductive O-ring 160 b, the signalwould see an inductive load. The material for regions 162, 164, 166 mayhave properties selected from a group comprising conductive, resistive,magnetic, dielectric, capacitive or semi-conductive and combinationsthereof. The design may be extended to circuit boards having fewer ormore internal layers than that described without departing from thespirit of the invention.

In addition, regions 162, 164, 166 may have electronic components 167,169, 171 embedded therein and connected as described herein. Also, asillustrated for component 171, a component may be found within one ormore regions within the body of a Z-directed component. Internalconnections may be provided from embedded components to O-rings 160 a,160 b. Alternatively, internal connections may be provided from theembedded components to plateable pads provided on the side surface 150s.

The various embodiments and features discussed for a Z-directedcomponent are meant to be illustrative and not limiting. A Z-directedcomponent may be made of a bulk material that performs a networkfunction or may have other parts embedded into its body. A Z-directedcomponent may be a multi-terminal device and, therefore, may be used toperform a variety of functions including, but not limited to:transmission lines, delay lines, T filters, decoupling capacitors,inductors, common mode chokes, resistors, differential pair passthroughs, differential ferrite beads, diodes, or ESD protection devices(varistors). Combinations of these functions may be provided within onecomponent.

FIG. 7 illustrates various example configurations for a conductivechannel in a Z-directed component. As shown, channel 90 has a region 92intermediate the ends comprising a material having properties selectedfrom a group comprising conductive, resistive, magnetic, dielectric,capacitive or semi-conductive properties and combinations thereof. Thesematerials form a variety of components. Additionally, a component may beinserted or embedded into region 92 with portions of the conductivechannel extending from the terminals of the component. A capacitor 92 amay be provided in region 92. Similarly, a diode 92 b, a transistor 92 csuch as a MOSFET 92 d, a zener diode 92 e, an inductor 92 f, a surgesuppressor 92 g, a resistor 92 h, a diac 92 i, a varactor 92 j andcombinations of these items are further examples of materials that maybe provided in region 92 of conductive channel 90. While region 92 isshown as being centered within the conductive channel 90, it is notlimited to that location.

For a multi-terminal device such as transistor 92 c, MOSFET 92 d, anintegrated circuit 92 k, or a transformer 92 l, one portion of theconductive channel may be between the top surface trace and a firstterminal of the device and the other portion of the conductive channelbetween the bottom surface trace and a second terminal of the device.For additional device terminals, additional conductors may be providedin the body of the Z-directed component to allow electrical connectionto the remaining terminals or additional conductive traces may beprovided within the body of the Z-directed component between theadditional terminals and channels on the side surface of the body of aZ-directed component allowing electrical connection to an externalconductive trace. Various connection configurations to a multipleterminal device may be used in a Z-directed component.

Accordingly, those skilled in the art will appreciate that various typesof Z-directed components may be utilized including, but not limited to,capacitors, delay lines, transistors, switches, and connectors. Forexample, FIGS. 8 and 9 illustrate a Z-directed component termed a signalpass-through that is used for passing a signal trace from the topsurface of a PCB to the bottom surface.

Z-Directed Signal Pass-Through Component

FIG. 8 shows a sectional view taken along line 8-8 in FIG. 9 of a PCB200 having 4 conductive planes or layers comprising, from top to bottom,a ground (GND) plane or trace 202, a voltage supply plane V_(CC) 204, asecond ground GND plane 206 and a third ground GND plane or trace 208separated by nonconductive material such as a phenolic plastic such asFR4 which is widely used as is known in the art. PCB 200 may be used forhigh frequency signals. The top and bottom ground planes or traces 202and 208, respectively, on the top and bottom surfaces 212 and 214,respectively, of PCB 200 are connected to conductive traces leading upto Z-directed component 220. A mounting hole 216 having a depth D in anegative Z direction is provided in PCB 200 for the flush mounting ofZ-directed component 220. Here depth D corresponds to the thickness ofPCB 200; however, depth D may be less than the thickness of PCB 200creating a blind hole therein. Mounting hole 216, as illustrated, is athrough-hole that is round in cross-section to accommodate Z-directedcomponent 220 but may have cross sections to accommodate the insertionof Z-directed components having other body configurations. In otherwords, mounting holes are sized so that Z-directed components areinsertable therein. For example, a Z-directed component having acylindrical shape may be inserted into a square mounting hole and viceversa. In the cases where Z-directed component does not make a tightfit, resist materials will have to be added to the areas of thecomponent and PCB where copper plating is not desired.

Z-directed component 220 is illustrated as a three lead component thatis flush mounted with respect to both the top surface 212 and bottomsurface 214 of PCB 200. Z-directed component 220 is illustrated ashaving a generally cylindrical body 222 of a length L. A centerconductive channel or lead 224, illustrated as being cylindrical, isshown extending the length of body 222. Two concave side wells orchannels 226 and 228, which define the other two leads, are provided onthe side surface of Z-directed component 220 extending the length ofbody 222. Side channels 226 and 228 are plated for making electricalconnections to Z-directed component 220 from various layers of PCB 200.As shown, the ground plane traces on layers 202, 206, and 208 of PCB 100are electrically connected to side channels 226 and 228. V_(CC) plane204 does not connect to Z-directed component 220 as shown by the gap 219between V_(CC) plane 204 and wall 217 of mounting hole 216.

FIG. 9 illustrates a top view of Z-directed component 220 in PCB 200.Three conductive traces 250, 252 and 254 lead up to the edge of wall 217of mounting hole 216. As illustrated, trace 252 serves as ahigh-frequency signal trace to be passed from the top surface 212 to thebottom surface 214 of PCB 200 via Z-directed component 220. Conductivetraces 250 and 254 serve as ground nets. Center lead or conductivechannel 224 is electrically connected to trace 252 on the top surface212 of PCB 200 by a top trace 245 and plating bridge 230. Top trace 245on the top surface of Z-directed component 220 extends from the top end224 t of conductive channel 224 to the edge of Z-directed component 220.Although not shown, the bottom side of Z-directed component 220 andbottom surface 214 of PCB 200 is configured in a similar arrangement oftraces as shown on top surface 212 of PCB 200 illustrated in FIG. 12. Abottom trace on the bottom surface of Z-directed component 220 extendsfrom bottom of conductive channel 224 to the edge of Z-directedcomponent 220. A plating bridge is used to make the electricalconnection between the bottom trace and another high frequency signaltrace provided on the bottom surface of PCB 200. The transmission lineimpedance of the Z-directed component can be adjusted to match the PCBtrace impedance by controlling the conductor sizes and distances betweeneach conductor which improves the high speed performance of the PCB.

During the plating process, wells 256 and 258 formed between wall 217 ofmounting hole 216 and side channels 226 and 228 allow plating materialor solder pass from the top surface 212 to the bottom surface 214electrically interconnecting traces 250 and 254, respectively to sidechannels 226 and 228, respectively, of Z-directed component 220 and alsoto similarly situated traces provided on the bottom surface 214 of PCB200 interconnecting ground planes or traces 202, 206 and 208. Theplating is not shown for purposes of illustrating the structure. In thisembodiment, V_(CC) plane 204 does not connect to Z-directed component220.

One of the challenges for high frequency signal speeds is thereflections and discontinuities due to signal trace transmission lineimpedance changes. Many PCB layouts try to keep high frequency signalson one layer because of these discontinuities caused by the routing ofsignal traces through the PCB. Standard vias through a PCB have to bespaced some distance apart which creates high impedance between thesignal via and the return signal via or ground via. As illustrated inFIGS. 8 and 9, the Z-directed component and the return ground or signalshave a very close and controlled proximity that allow essentiallyconstant impedance from the top surface 212 to the bottom surface 214 ofPCB 200.

A Z-directed signal pass through component may also comprise adecoupling capacitor that will allow the reference plane of a signal toswitch from a ground plane, designated GND, to a voltage supply plane,designated V_(CC), without having a high frequency discontinuity. FIG.10 shows a cross-sectional view of a typical 4-layer PCB 300 with asignal trace 302 transferring between the top layer 304 and the bottomlayer 306. Z-directed component 310, similar to that shown in FIG. 5D,having body 312 connects signal trace 302 through center conductivechannel 314. Z-directed component 310 also comprises plated sidechannels 316 and 318 extending along the side surface 312 s of the body312. The top 314 t and bottom 314 b of conductive channel 314 areconnected to conductive traces 318 t and 318 b on the top 312 t andbottom 312 b of body 312. These, in turn, are connected to signal trace302 via top and bottom plating bridges 330 t and 330 b. Side channels316 and 318 are plated to GND plane 332 and V_(CC) plane 334,respectively. Connection points 336 and 338, respectively, illustratethis electrical connection. Schematically illustrated decouplingcapacitor 350 is internal to body 312 and is connected between sidechannels 316 and 318. Decoupling capacitor 350 may be a separatecapacitor integrated into the body 312 of Z-directed component 310 or itcan be formed by fabricating a portion of the body 312 of Z-directedcomponent 310 from the required materials with dielectric propertiesbetween conductive surfaces.

The path for signal trace 302 is illustrated with diagonal hatching andcan be seen to run from top layer 304 to bottom layer 306. GND plane 332and side channel 316 are electrically connected at 336 with the signalpath return indicated by the dark stippling 362. V_(CC) plane 334 andside channel 318 are electrically connected at 338 with the signal pathreturn indicated by the light stippling 364. As is known in the art,where a signal plane or trace is not to be connected to the insertedpart, those portions are spaced apart from the component as shown at370. Where a signal plane or trace is to be connected to an insertedcomponent, the signal plane or trace is provided at the wall or edge ofthe opening to allow the plating material or solder to bridgetherebetween as illustrated at points 330 t, 330 b, 336, and 338.

The vertically hatched portion 380 shows the high speed loop areabetween the signal trace and return current path described by the signaltrace 302 and the GND plane 332 or V_(CC) plane 334. The signal trace302 on the bottom surface 306 is referenced to power plane V_(CC) 334that is coupled to the GND plane 332 through decoupling capacitor 350.This coupling between the two planes will keep the high frequencyimpedance close to constant for the transition from one return plane toanother plane of a different DC voltage.

Internally mounting Z-directed components in a PCB greatly facilitatesthe PCB technique of using outer ground planes for EMI reduction. Withthis technique, signals are routed on the inner layers as much aspossible. FIG. 11 illustrates one embodiment of this technique. PCB 400is comprised of, from top to bottom, top ground layer 402, internalsignal layer 404, internal signal layer 406 and bottom ground layer 408.Ground layers 402 and 408 are on the top and bottom surfaces 400 t and400 b of PCB 400. A mounting hole 410, shown as a through-hole, extendsbetween the top and bottom surfaces 400 t and 400 b. Z-directedcomponent 420 is shown flush mounted in PCB 400. Z-directed component420 comprises body 422 having a center region 424 intermediate the top422 t and bottom 422 b of body 422 and two side channels 425 and 427 onside surface 422 s.

Side channels 425 and 427 and wall 411 of hole 410 form plating wells413 and 415 respectively. Center region 424 is positioned within body422 and extends a distance approximately equal to the distanceseparating the two internal signal layers 404 and 406. Side channel 425extends from the bottom surface 422 b of body 422 to internal signallevel 406 while side channel 427 extends from top surface 422 t of body422 to internal signal level 404. Here, side channels 425 and 427 extendonly along a portion of side surface 422 s of body 422. Conductivechannel 426 extends through center region 424 but does not extend to thetop and bottom surfaces 422 t, 422 b of body 422. FIG. 5H illustrates apartial channel similar to side channel 427. Conductive channel 426 hasconductive traces 428 t and 428 b extending from the top 426 t andbottom 426 b of conductive channel 426 to side channels 427 and 425,respectively. While illustrated as separate elements, conductive channel426 and traces 428 t, 428 b may be one integrated conductor electricallyinterconnecting side channels 425, 427. As shown, conductive trace 428 bis connected to internal signal layer 406 via plated side channel 425and well 413 while trace 428 t connects to internal signal level 404 viaside channel 427 and well 415. Ground layers 402 and 408 are notconnected to Z-directed component 420 and are spaced away from mountinghole 410 as previously described for FIGS. 8 and 10. As shown by doubleheaded dashed arrow 430, a signal on signal layer 406 can be via'd tosignal layer 404 (or vice versa) via Z-directed component 420 through apath extending from well 413, side channel 425, trace 428 b, conductivechannel 426, trace 428 t, side channel 427, and well 415 to allow thesignal to remain on the inner layers of PCB 400 with ground layers 402and 408 providing shielding.

Z-Directed Decoupling Capacitors

FIGS. 12 and 13 illustrate two additional example Z-directed componentsin the form of decoupling capacitors. In FIG. 12, a Z-directed capacitor500 is shown with a body 502 having a conductive channel 504 and twoside channels 506 and 508 extending along its length similar to thosepreviously described. Conductive channel 504 is shown connected to asignal 526. Vertically oriented interleaved partial cylindrical sheets510, 512 forming the plates of Z-directed capacitor 500 are connected toreference voltages such as voltage V_(CC) and ground (or any othersignals requiring capacitance) and are used with intervening layers ofdielectric material (not shown). Partial cylindrical sheet 510 isconnected to plated channel 506 which is connected to ground 520.Partial cylindrical sheet 512 is connected to plated channel 508 whichis connected to supply voltage V_(CC) 522. Sheets 510, 512 may be formedof copper, aluminum or other material with high conductivity. Thematerial between the partial cylindrical sheets is a material withdielectric properties. Only one partial cylindrical sheet is shownconnected to each of V_(CC) 522 and ground 520; however, additionalpartial cylindrical sheets may be provided to achieve the desiredcapacitance/voltage rating.

Another embodiment of a Z-directed capacitor is shown in FIG. 13 usingstacked support members connected to voltage V_(CC) or ground.Z-directed capacitor 600 is comprised of center conductive channel 601and a body 605 comprised of a top member 605 t, a bottom member 605 b,and a plurality of support members 610 (illustrated as disks) betweenthe top and bottom members 605 t, 605 b.

Center conductive channel 601 extends through openings 615 in theassembled Z-directed capacitor 600 and openings 602 t and 602 b, all ofwhich are sized to closely receive the center conductor. Centerconductive channel 601 is electrically connectable to conductive traces603 t and 603 b on the top and bottom portions 605 t, 605 b forming asignal path for signal 626. This connection is made by plating orsoldering. Center conductive channel 601 is connected to signal 626 viaconductive trace 603 t. The bottom end of conductive channel 601 isconnected in a similar fashion to a signal trace (not shown) viaconductive trace 603 b.

Opposed openings 607 t and 608 t are provided at the edge of top portion605 t. Bottom portion 605 b is of similar construction as top portion605 t having opposed openings 607 b and 608 b provided at the edge.Between top and bottom portions 605 t, 605 b are a plurality of supportmembers 610, which provide the capacitive feature. Support members 610each have at least one opening 613 at their outer edge and an inner hole615 allowing for passage of conductive channel 601 therethrough. Asshown, two opposed openings 613 are provided in each support member 610.When assembled, the opposed openings 607 t, 607 b, 608 t, 608 b, and 613align to form opposed side channels 604 and 608 extending along the sidesurface of Z-directed capacitor 600. Side channel 604 is shown connectedto reference voltage such as ground 620 and side channel 606 to anotherreference voltage such as V_(CC) 622. Support members 610 may befabricated from a dielectric material and may be all of the same orvarying thickness allowing for choice in designing the desiredproperties for Z-directed capacitor 600.

Annular plating 617 is provided on one of top and bottom surfaces ofsupport member 610 or, if desired, on both surfaces. Annular plating isshown on the top surface of each support member but location of theannular plating can vary from support member to support member. Annularplating 617 generally conforms to the shape of the support member andextends from one of the edge openings 613 toward the other if anadditional opening is provided. The annular plate 617 is of a diameteror dimension or overall size that is less than the diameter, dimensionor overall size of support member 610 on which it is affixed. While theplate 617 is described as annular, other shapes may also be usedprovided that the plating does not contact the center conductive channelor extend to the edge of the support member on which it is plated orotherwise affixed. The annular plate does contact one of the edgeopenings 613 but is spaced apart from the other openings if more thanone channel is present in the side surface of the body of Z-directedcapacitor 600. Also, there is an opening 619 in annular plate 617 havinga larger diameter than opening 615 in annular plate 617 through whichconductive channel 601 passes. Opening 619 has a larger diameter thanthat of conductive channel 601 leaving annular plate 617 spaced apartfrom conductive channel 601.

As illustrated, the support members 610 are substantially identicalexcept that when stacked, alternate members are rotated 180 degrees withrespect to the member above or below it. This may be referred to as a1-1 configuration. In this way, alternate members will be connected toone or the other of the two side channels. As shown in FIG. 13, theannular plating on the upper one of the two support members 610 isconnected to side channel 608 and voltage V_(CC) 622 while the annularplating on the lower one of the two support members 610 is connected toside channel 604 and ground 620. Other support member arrangements mayalso be used such as having two adjacent members connected to the samechannel with the next support member being connected to the oppositechannel which may be referred to as a 2-1 configuration. Otherconfigurations may include 2-2, 3-1 and are a matter of design choice.The desired capacitance or voltage rating determines the number ofsupport members that are inserted between top and bottom portions 605 t,605 b. Although not shown, dielectric members comprised of dielectricmaterial and similarly shaped to support members 610 may be interleavedwith support members 610. Based on design choice, only a single channelmay be used or more channels may be provided and/or the annular platingmay be brought into contact with the center conductive channel and notin contact with the side channels. Again, the embodiments for Z-directedcapacitors are for purposes of illustration and are not meant to belimiting.

With either design for a Z-directed capacitor, a second conductivechannel may be provided in parallel with the first conductive channelthat is disposed within the conductive plates to create a differentialdecoupling capacitor. Another embodiment of a Z-directed capacitor canbe constructed from FIG. 12 or FIG. 13 by connecting the centerconductive channel to one of the reference voltages at each supportmember that also has its annular plating connected to the same referencevoltage. This may be accomplished simply by connecting the conductivechannel to the annular plating as schematically illustrated by thejumper 621. In practice, the annular opening 619 in the annular plate617 would be sized so that the annular plate and conductive channel 601would be electrically connected. This component may be placed directlybelow a power pin or ball of an integrated circuit or other surfacemounted component for optimum decoupling placement.

Again, the Z-directed signal pass-through components illustrated inFIGS. 8-11 and the Z-directed decoupling capacitors illustrated in FIGS.12 and 13 provide merely a few example applications of a Z-directedcomponent. Those skilled in the art will appreciate that various othertypes of Z-directed components may be utilized including, but notlimited to, transmission lines, delay lines, T filters, decouplingcapacitors, inductors, common mode chokes, resistors, differential pairpass throughs, differential ferrite beads, diodes, or ESD protectiondevices (varistors).

Extrusion Process for Manufacturing a Z-Directed Component

An extrusion process for manufacturing the Z-directed components on acommercial scale is provided. In the extrusion process, the bodies ofthe Z-directed components are formed from a material forming thecomponent substrate. As needed, the substrate material may also be mixedwith a binder material as is known in the art. As discussed above, avariety of different Z-directed components are contemplated hereinincluding, but not limited to, transmission lines, delay lines, Tfilters, decoupling capacitors, inductors, common mode chokes,resistors, differential pair pass throughs, differential ferrite beads,diodes, and ESD protection devices (varistors). Accordingly, it will beappreciated that the substrate material used will depend on theZ-directed component desired. The substrate material may include asingle dielectric material that has a relative permittivity from about3, e.g., polymers, to over 10,000, e.g., barium titanate (BaTiO₃). Forexample, a material with a relatively high dielectric value may be usedin a Z-directed decoupling capacitor and a material with a relativelylow dielectric value may be used in a Z-directed signal pass-throughcomponent. If a Z-directed component is desired to have an inductivefunction or a delay line then a ferrite material may be selected thathas a low or high relative permeability with a range of about 1 to about50,000. If a Z-directed component is desired to have some degree ofconductivity then a conductive material may be mixed with a dielectricmaterial to create a desired resistance. Depending on the function ofthe Z-directed component desired, these or other compatible materialsmay be mixed together to form a component layer.

With reference to FIGS. 14A and 14B, an extrusion die 700 defining theshape of the Z-directed component layer(s) according to one embodimentis illustrated. Extrusion die 700 includes a chamber 703 having an inlet701 and an outlet 702 for passing the component substrate materialtherethrough. In the example embodiment illustrated, a generallycylindrical chamber 703 is used; however, as discussed above, manydifferent shapes may be used. In this embodiment, an interior projection704 is provided that forms a corresponding interior channel in thecomponent layer(s). A pair of projections 705, 706 along an edge 703 eof chamber 703 are also included that form a corresponding pair of sidechannels in the component layer(s). In the example embodimentillustrated, projection 704 is cylindrical and projections 705, 706 aresemi-cylindrical; however, any suitable shape may be used as desireddepending on the desired shape of the channels in the componentlayer(s). Further, although one interior projection 704 and two sideprojections 705, 706 are illustrated; any suitable number of side and/orinterior projections may be used depending on the desired number of sideand interior channels, respectively, through the component layer(s).

It will be appreciated that where extrusion die 700 includes one or moreinterior projections for forming an interior channel in the componentlayer(s), such as interior projection 704, a support member 707 isneeded to physically support the interior projection from one or morepoints along edge 703 e of chamber 703. In the example embodimentillustrated, support member 707 connects interior projection 704 withboth side projections 705, 706 to support interior projection 704.

One or more layers of the Z-directed component are formed by forcing ablank 708 containing the substrate material through extrusion die 700using a ram (not shown). In one embodiment, blank 708 is composed ofgreen (unfired) ceramic; however, various substrate materials may beused as discussed above. Specifically, blank 708 is pressed into inlet701 through chamber 703 which causes the substrate material to take onthe shape of chamber 703. As the substrate material is forced throughchamber 703, projections 704, 705, 706 form the desired channels throughthe substrate material. A direct extrusion process may be used whereextrusion die 700 is held stationary and the ram is moved towards it oran indirect extrusion process may be used where the ram is heldstationary and extrusion die 700 is moved towards it. A combination ofthe two may be also used where the ram and die 700 are moved towardseach other. Alternatively, a hydrostatic extrusion process may be usedwhere fluid pressure is used to force blank 708 through die 700.Extrusion die 700 may be oriented horizontally, vertically or at anysuitable angle thereto. Any conventional drive may be applied to providethe extruding force including a mechanical or hydraulic drive.

It will be appreciated that where one or more interior projections, suchas projection 704, are included in extrusion die 700, the correspondingsupport member 707 will create an undesired gap in the extrudedsubstrate material. Support member 707 is preferably thin in order tominimize the size of this gap. For example, when the extrusion die 700illustrated in FIGS. 14A and 14B is used, the substrate material isdivided in half by support member 707. With reference to FIG. 15A, whichshows a cutaway view of chamber 703, one way to remove this gap, shownas gap 710, is to recombine the halves 708 a, 708 b of the substratematerial in the output 702 of chamber 703 (or a separate chamberattached thereto). The diameter of chamber 703 (or width in the case ofa chamber having a non-circular cross-section) may decrease slightly inthe downstream direction D of extrusion past projections 704, 705, 706in order to urge halves 708 a, 708 b toward each other. As shown in FIG.15A, this causes gap 710 to reduce as the substrate material advancesuntil halves 708 a, 708 b combine to eliminate gap 710. Further, thedownstream edge of support member 707 may taper like a blade such thatits thickness decreases in downstream direction D in order to promoterecombination of halves 708 a, 708 b. The upstream edge of supportmember 707 may also taper to provide a cleaner cut into blank 708 inorder to facilitate recombination.

It will be appreciated that care must be taken to prevent the channelsformed by projections 704, 705, 706 from narrowing or losing theirshapes as the substrate material advances. In the example embodimentshown in FIG. 15B, which shows a cutaway view of chamber 703, a movableelement 712, such as a plug or rod, supports the downstream end of thesubstrate material as it advances to help prevent the channels fromnarrowing as gap 710 is eliminated. For instance, where the extrusionprocess is performed in a vertically downward direction, plug 712supports the substrate material from below and lowers according to thespeed of extrusion in order to maintain the shape of the substratematerial. Projections 704, 705, 706 can also be extended in downstreamdirection D as desired to prevent the channels from losing their shape.Further, where some narrowing of the channels in the substrate materialis anticipated, it can be accounted for by initially making the channelsslightly larger than desired and allowing them to narrow to theirdesired size and shape. In this manner, the substrate material exitingextrusion die 700 includes the desired channels therein but not theundesired gap 710 caused by support member 707.

With reference to FIG. 16, an alternative for forming interior channelsin the component layer(s) without forming an undesired gap is to extrudethe material in separate segments, such as halves, and then to combinethe segments after extrusion. For example, where an extrusion die havingan interior support member (such as support member 707 of extrusion die700 shown in FIGS. 14A and 14B) is used, instead of recombining thesegments in the output of the chamber as discussed above related toFIGS. 15A and 15B, the halves may be removed from the extrusion die andthen combined. Further, where the segments of the extruded material tobe combined are symmetrical, a common extrusion die may be used toextrude each segment separately. Conversely, where the segments areasymmetrical, multiple extrusion dies will be used. In the exampleembodiment illustrated, an extrusion die 720 having an inlet 721, andoutlet 722 and a chamber 723 is used to form the component layer(s) inhalves. Extrusion die 720 includes a projection 724 for forming aninterior channel and a projection 726 for forming a side channel in thecomponent layer(s). Projections 724, 726 are each positioned along anedge 723 e of chamber 723 thereby eliminating the need for an interiorsupport member, such as support member 707 shown in FIG. 14B. In theembodiment illustrated in FIG. 16, projection 726 is sized and shaped toform a complete side channel through each extruded segment. In contrast,projection 724 is sized and shaped to form only a partial interiorchannel through each extruded segment such that when the extrudedsegments are combined, the corresponding partial interior channelscreated by projection 724 are combined to form a complete interiorchannel through the component layer(s). Specifically, the void createdby projection 724 in a first extruded segment is matched with acorresponding void created by projection 724 in a second extrudedsegment to create a complete interior channel in the component layer(s).The void created by projection 726 in the first extruded segment createsa first side channel in the component layer(s) and the void created byprojection 726 in the second extruded segment creates a second sidechannel in the component layer(s).

The corresponding extruded segments can be combined by matably aligningthe segments and then applying a substantially uniform radial pressure.In the unfired state, the extruded segments will tend to adhere to oneanother upon being pressed together by the applied radial pressure. Anadhesive could also be used to join the segments to each other. Theadhesive can be baked off when the substrate material is fired or it canbe a high temperature adhesive that survives the firing process providedthat the impurity in the substrate material caused by the adhesive willnot inhibit performance of the Z-directed component.

Another alternative for forming interior channels in the componentlayer(s) without forming an undesired gap is to simply extrude thelayer(s) using an extrusion die that does not include any interiorprojections that require support and then form the desired interiorchannel(s) after the extrusion process is completed. The desiredinterior channel(s) may be formed by conventional methods known in theart such as drilling or laser cutting through the extruded substratematerial.

After the substrate material has been extruded in the shape of thecomponent layer(s), if desired, the substrate material can be partiallyfired in order to improve the strength of the material and to ensurethat it will remain intact before proceeding with the remaining steps.After the substrate material is extruded, it may be cut into two or moreindividual component layers depending on the particular Z-directedcomponent being made. For example, if the Z-directed component isintended to possess significant capacitance between any of theconductive paths the substrate material will be layered. Alternatively,if the Z-directed component only requires interior and/or side channelsfor signal and ground return paths, then the entire Z-directed componentmay be extruded at once. Conductive material can then be applied to theinterior and/or side channels and across the top and/or bottom surfaceof the component to provide one or more traces for connection with thePCB as discussed below.

FIG. 17 shows a segment of extruded substrate material 730 ready to becut. One option is to use a series of blades 732 spaced according to apredetermined distribution to create the component layers. In oneembodiment, the component layers range in thickness from 0.5 mil toabout 62 mil (about 0.0127 mm to about 1.57 mm), including allincrements and values therebetween, depending on the application inwhich the Z-directed component will be used. Another option is to cutthe extruded substrate material 730 using multiple passes of a singleblade. In this embodiment, the thickness of each component layer isdetermined by controlling the timing of each pass of the blade. Eachcomponent layer may have substantially the same thickness or differentthicknesses may be used. A feedback mechanism may be used to adjust thetiming of the cuts in order to account for parameters that may changewith blade usage, such as the kerf of the blade.

FIG. 18 shows a post-cut layer 740 of the Z-directed component formed byextrusion die 700. Layer 740 includes one center channel 742 a and twoside channels 742 b, 742 c that correspond with projections 704, 705 and706, respectively. As discussed above, the shape of layer 740 and thenumber of channels 742 therein, as well as their placement and shape,can be altered by the changing the shape of the extrusion die chamberused including the number and placement of projections therein. At thispoint, layer 740 is ready to receive conductive material on at least onesurface thereof. Conductive material may be applied to one or more ofchannels 742 a, 742 b, 742 c, a top surface 740 t and/or both topsurface 740 t and a bottom surface of layer 740. Layer 740 istransferred to a tool having restraining and locating ability, such as aconveyor belt, to receive conductive material. If it is desired to plateone or more side channels in the component layer 740, such as sidechannels 742 b, 742 c, layer 740 may be placed in a cavity 744 in aconstraining plate 746 that has a side wall surface 748 that is spacedfrom the side channels 742 b, 742 c in the component layer 740 such thata gap 749 is formed therebetween (FIG. 19). This spacing allowsconductive material to flow into gap 749 to plate the desired sidechannel(s) 742 b, 742 c. Another alternative to plate side channels 742b, 742 c is to apply conductive material after the Z-directed componenthas been assembled by painting, jetting, sputter, or other knownmethods.

A number of different methods may be used to apply conductive materialto layer 740. For example, in one embodiment, a mask is applied to topsurface 740 t that restricts the application of conductive material toselected portions of top surface 740 t. Conductive material is thenscreened through the mask onto the component layer 740. FIG. 20 shows anexample mask in the form of a physical mask 750 that is placed on topsurface 740 t of layer 740. The diagonal hatching included in FIG. 20illustrates the openings in mask 750. Mask 750 includes a center opening752 that permits conductive material to flow into and plate centerconductive channel 742 a. Mask 750 also includes a pair of peripheralopenings 754 a, 754 b that permit conductive material to plate topsurface 740 t. Peripheral openings 754 a, 754 b are separated by a thinmask portion 756 that also separates center opening 752 from peripheralopenings 754 a, 754 b. Portion 756 is required when one or moreconductive channels through the interior of the layer 740 are desired inorder to provide one or more interior openings in the mask such ascenter opening 752 in mask 750. Mask 750 includes a pair of scallopedportions 758 a, 758 b that are positioned above side channels 742 b, 742c in the example embodiment illustrated. Scalloped portion 758 bprojects slightly further inward than scalloped portion 758 a. As aresult, in this example embodiment, conductive material is permitted toflow onto the portion of top surface 740 t that connects with sidechannel 742 b but conductive material is not permitted to connect withside channel 742 c.

The resulting plated layer 740 utilizing example mask 750 is shown inFIG. 21 having conductive material 760 thereon. As shown, center channel742 a has been plated with conductive material 760. Top surface 740 t oflayer 740 has been plated to make a connection with side channel 742 bbut not side channel 742 c. The mask 750 shown in FIG. 20 is intended toillustrate one example of a suitable mask. Alternative masks may beemployed depending on such factors as the shape of the layer, the numberof center channels and/or side channels that require plating, and theplating pattern desired for top surface 740 t.

As an alternative to a physical mask, such as mask 750, a photoresistmask may be applied using photochemical methods known in the art. Inthis embodiment, a radiation-sensitive photoresist is applied to topsurface 740 t and then selectively exposed to a radiation source, suchas X-ray or UV light. The photoresist is then developed to wash away theareas where the photoresist layer is not desired. It will be appreciatedthat positive or negative photoresists may be used as desired.Conductive material can then be screened through the photoresist maskonto top surface 740 t of the component layer 740 such as by spincoating liquid conductive material on top of the photoresist mask. Afterthe conductive material is applied, the remaining photoresist can thenbe removed.

In another embodiment, instead of using a mask, a selective jettingprocess is used to apply conductive material to top surface 740 t and/orchannel(s) 742. In this embodiment, liquid conductive material isapplied to the component layer 740 using a fluid ejection mechanism asis known in the art. Where an etchable conductive material is used,another alternative is to spin coat or otherwise apply a layer of liquidconductive material across the entire top surface 740 t and thenselectively etch the conductive material from top surface 740 t to formthe desired conductive pattern thereon.

Another alternative is to first selectively apply a seed layer ofconductive material to the component layer 740 and then apply additionalconductive material by electrolysis techniques. One suitable method forapplying the seed layer includes the use of photochemical methods. Aphotoresist layer is applied across the entire top surface 740 t of theZ-directed component layer 740 and then selectively exposed to aradiation source. The photoresist is then developed to wash away theareas where the photoresist layer is not desired. Again, positive ornegative photoresists may be used as desired. Conductive material isthen applied across the entire top surface 740 t of the Z-directedcomponent layer 740. The remainder of the photoresist is then etchedaway thereby also removing the conductive material from those areaswhere the seed layer is not desired. Electrolysis techniques are thenapplied to thicken the layer of conductive material on the componentlayer 740.

The various methods for applying conductive material to the Z-directedcomponent layer described herein are equally applicable where it isdesired to apply a material other than conductive material such as, forexample resistive, magnetic, dielectric, or semi-conductive material tocomponent layer 740. It will be appreciated that channel(s) 742 do notneed to be plated after each layer is formed. Rather, channel(s) 742 maybe filled with conductive material after the component layers arestacked together.

The Z-directed component is formed from a stack of component layers 740.Each layer may be formed from the same substrate material or some layersmay be formed from different substrate materials. For example, aconveyor may be used to move all of the component layers 740 forstacking after they are formed. The outside features of the layers 740may be used to align the layers 740 with each other. With reference toFIGS. 22A and 22B, for a Z-directed capacitor 762, each layer 740 isalternatively stacked by rotating it 180 degrees with respect to thelayer 740 immediately below creating positive and negative terminals ontwo sides of the Z-directed component. The stacking is performed in aconstraining plate that keeps the stack in position.

In some embodiments, a Z-directed component 764 may be desired thatincludes partial side channels 742 that are twisted or offset from eachother between the top and bottom halves of the component 764 as shown inFIG. 23. This type of component may be desired in order to permit aninterior signal to enter on one side of the Z-directed component 764 andexit at a 90 degree angle thereto without running into a side channel742. This offset can be accomplished by rotating the layers 740 as theyare stacked.

In one embodiment, once the component layers are stacked, they arecompressed with moderate heat to create an aggregate that is solidenough to be removed from the constraining plate in which they arepositioned to be fired later. For example, FIG. 24 shows a cutaway viewof the stack of layers 740 positioned in a cavity 772 of a constrainingplate 770. A movable component, e.g., a rod or a plug, applies a desiredforce to one end of the stacked layers to create the desired pressureprofile for the materials chosen. In the example embodiment illustrated,opposing plugs 774, 776 apply pressure from opposite ends of the stackedlayers 740. Heating elements can be embedded into the walls of cavity772 in order to supply a desired temperature profile to the stackedlayers 740. Alternatively, rather than applying moderate heat, a fullfiring process is performed in plate 770. However, this may be difficultdue to the extreme temperatures that are subjected to the constrainingelements.

In some embodiments, a chamfer, dome or other form of taper or lead-inof at least one of the top and bottom edge of the Z-directed componentis desired in order to ease insertion of the Z-directed component intothe mounting hole in the PCB. For example, FIG. 25A shows a Z-directedcomponent 780 having a dome 782 formed on an end thereof. FIG. 25B showsa Z-directed component 784 having a chamfered end 786. The dome 782 orchamfer 786 may be part of the component or attached thereto. In oneembodiment, the dome 782 or chamfer 786 is a separate part that ispartially inserted into the mounting hole in the PCB. In thisembodiment, the Z-directed component is then inserted behind the dome782 or chamfer 786 to push it through the mounting hole causing the dome782 or chamfer 786 to expand the mounting hole and prevent the componentfrom cutting or tearing the PCB. Where the dome 782 or chamfer 786 isattached to the Z-directed component, it may be configured to remainattached to the Z-directed component following insertion into themounting hole in the PCB or it may be used to facilitate insertion andthen removed.

One method for forming the desired taper as part of the Z-directedcomponent utilizes a plug 790 having a recess 792 formed in an end 794thereof having a tapered rim 796 around a periphery of recess 792 asshown in FIG. 26. Tapered rim 796 is chamfered in the example embodimentillustrated; however, a domed, elliptical or rounded rim may also beused depending on the shape of the taper desired. Plug 790 is used tocompress the stacked component layers as discussed above. When plug 790applies a force to an end of the stacked layers, the end of the part isreflowed to have the desired geometry and the conductive path(s) on theend of the part are allowed to continue across or through thecorresponding taper formed on the end of the part. As a result, thetapered end portion of the part can then be used to facilitate board toboard electrical connections in multi-PCB applications. It will beappreciated that where the desired taper extends across multiplecomponent layers, successive layers of the Z-directed component formingthe taper will have decreasing diameters (or widths in the case of acomponent layer with a non-circular cross-section). Alternatively, thedesired taper may be formed in a single component layer.

After the aggregate Z-directed component has been formed, a firingprocess is applied to solidify the part if it has not been done soalready. The firing process also shrinks the part to its finaldimensions. At this point, the Z-directed component can be tested foryield and performance and any additional processes may be performed asdesired. For example, in some instances, the pressing and heating stepsmay cause burrs to form. Accordingly, in some embodiments, theZ-directed components are tumbled with various abrasive agents to smooththe corners and edges of the part. Further, resist areas may be added tothe Z-directed component to keep the conductive materials from stickingto areas that are not intended to be conductive. Glue areas may beapplied to the component to assist with retaining it in the PCB. Visiblemarkings and/or locating features may be added to the Z-directedcomponent to assist with assembly into the PCB.

Once production of the Z-directed component is complete, it is ready tobe inserted into the mounting hole of the PCB. As discussed above, thecomponent may be mounted normal to the plane of the PCB from the top orbottom surfaces or both surfaces, mounted at an angle thereto orinserted into the edge of the PCB between the top and bottom surfaces ofthe PCB. In some embodiments, the Z-directed component is press fit intothe mounting hole. This press fit may be in the form of an interferencefit between the component and the mounting hole. After the Z-directedcomponent is positioned in the mounting hole, a conductive platingbridge may be applied to connect one or more traces on the top and/orbottom surface of the component to a corresponding trace on the PCB.Further, where the Z-directed component includes side channels therein,such as side channels 742 b, 742 c, additional conductive plating may beapplied to these side channels to form the desired signal connectionsbetween the Z-directed component and the PCB.

With reference to FIG. 27, in one embodiment, after a Z-directedcomponent 800 is inserted into a mounting hole 802 in a PCB 804, anadhesive 806 is applied to a surface 808 of PCB 804 external to mountinghole 802. Adhesive 806 is positioned to contact a surface of Z-directedcomponent 800 when it is inserted into mounting hole 802 in order to fixthe location of Z-directed component 800 and prevent it from rotating ortranslating out of position.

With reference to FIGS. 28A and 28B, manufacturing variations in thethickness of the PCB and the length of the Z-directed component mayprevent the Z-directed component from being perfectly flush with boththe top and bottom surfaces of the PCB. As a result, in one embodiment,a conductive strip 812 is formed along a side surface 810 s of aZ-directed component 810. Conductive strip 812 runs along side surface810 s to either the top or bottom surface of Z-directed component 810.It will be appreciated that conductive strip 812 may be applied afterthe Z-directed component 810 is formed. Alternatively, conductive strip812 may be formed during fabrication of Z-directed component 810 such asby applying conductive material to a predetermined portion of thecomponent layer(s) 740 as discussed above. In the example embodimentillustrated, conductive strip 812 runs along side surface 810 s to a topsurface 810 t of Z-directed component 810. In this manner, conductivestrip 812 forms a bridge between a trace 814 on the respective top orbottom surface of Z-directed component 810 and a trace 816 on a PCB 818when the top or bottom surface of the Z-directed component extends pastthe corresponding top or bottom surface of the PCB. As a result, trace814 on Z-directed component 810 is able to connect to trace 816 on PCB818 even if the top or bottom surface of Z-directed component 810 is notflush with the corresponding top or bottom surface of PCB 818. In theexample configuration illustrated in FIG. 28B, conductive strip 812 runsfrom top surface 810 t of Z-directed component 810 to a point along sidesurface 810 s that is below the top surface of the PCB 818. In oneembodiment, conductive strip 812 extends into the side of Z-directedcomponent 810 both to decrease its resistance and to ensure that it isnot removed if another feature such as a taper is later applied toZ-directed component 810.

The foregoing description of several embodiments has been presented forpurposes of illustration. It is not intended to be exhaustive or tolimit the application to the precise forms disclosed, and obviously manymodifications and variations are possible in light of the aboveteaching. It is understood that the invention may be practiced in waysother than as specifically set forth herein without departing from thescope of the invention. It is intended that the scope of the applicationbe defined by the claims appended hereto.

What is claimed is:
 1. A method for manufacturing a Z-directed componentfor insertion into a mounting hole in a printed circuit board,comprising: extruding a substrate material through an extrusion diehaving a chamber defining the shape of the extruded substrate materialincluding forming at least one channel through the substrate materialwith a corresponding projection in the extrusion die; dividing theextruded substrate material into a plurality of layers of the Z-directedcomponent according to the thickness of each layer; applying aconductive material to a surface of at least one of the layers; andcombining a stack of the layers to form the Z-directed component.
 2. Themethod of claim 1, further comprising extruding the substrate materialin longitudinal segments and combining the longitudinal segmentsaccording to the shape of the Z-directed component, wherein theprojection is positioned along an edge of the chamber and forms apartial channel in each extruded segment, and a complete channel isformed in an interior portion of the substrate material when thesegments are combined.
 3. The method of claim 1, wherein the projectionis spaced inward from an edge of the chamber and connected to the edgeof the chamber by a support member, and a gap formed in the extrudedsubstrate material by the support member is eliminated by rejoiningcorresponding portions of the substrate material.
 4. The method of claim3, wherein the corresponding portions of the substrate material arerejoined after extrusion is complete.
 5. The method of claim 3, whereinthe corresponding portions of the substrate material are rejoined in acontinuous process downstream from extrusion.
 6. The method of claim 5,further comprising supporting the extruded longitudinal segments with amoving member from a downstream end of the substrate material as itadvances.
 7. The method of claim 1, wherein combining the stack of thelayers to form the Z-directed component includes heating and compressingthe stacked layers to form an aggregate part.